Solar Tracker

[tsbrownie]

Seems like all these trackers with their computer controls and all, use more electricity than they put out. It's more practical just to put up more panels at different angles.

[aaqilkhan]

@tsbrownie - i installed a 2kW system using my tracker. The system controller along with the drive system consumes a very small percentage of the power it produces. The surplus is stored in battery bank and converted to AC power. By the way, where did you get your statistics that it consumes more power than it puts out? Have you actually calculated/measure or just "baseless assumption"?

[tsbrownie]

@aaqilkhan Many systems use laptops (mine's 78 watts), motor(s) (24v X say 3 amps? = 72 more watts). Controller or other logic, 25 more watts? 175 watts so far. That's not including efficiency loss in controls nor power used for maintenance (cleaning, repairs, etc.) & power lost when the tracker does not work --> efficiencies are < normal. All fair game when talking about total outputs of systems). So 10% of a 2 KW system is in moving it? In smaller the % is higher. Fixed may be better.

[enticed2zeitgeist]

@tsbrownie I've heard solar panel trackers gain between 15-50% efficiency when they face the sun directly. It takes surprisingly very little to power to rotate the panel in most cases because they are usually balanced evenly. Also, just because the sun moves all day long at a very slow rate doesn't mean the panel is. The panels probably only move once every 5-15 minutes. I have tried to build a solar tracker with Arduino, the photo diodes aren't as sensitive as you might think.

[aaqilkhan]

@enticed2zeitgeist Using photo diodes isn't very efficient, as the failure of one diode can render the whole apparatus useless. My system uses embedded PIC controller programmed to compute the astronomical position of the sun and corrects the position when the error between current and calculated position varies by a certain angle (programmable value). Its more efficient than using photo diodes - which also have problem of shadows etc.

[enticed2zeitgeist]

@aaqilkhan Excellent. Sounds high tech lol. My comment was directed at you though. I was telling tsbrownie that solar trackers improve the efficiency of the panels a worthwhile amount.

[tsbrownie]

@enticed2zeitgeist You are correct, they gain a lot when they are accurately pointed from my personal tests. I am really thinking KISS (keep it simple / smart). All that stuff will make it more efficient on short time scales, but in the long run one must count all the power used to aim as well as in production and maintenance (and power lost from tracking failures) on the total system to determine if it's worthwhile. I'm "guesstimating" it's close / not worthwhile.

[enticed2zeitgeist]

@tsbrownie I don't think traditional solar panels are a wise solution at all for the same reasons you have just stated. I think Solar Stirling generators or heat differential methods are much more direct and do require expensive equipment to produce. Also the chances of them breaking down are much less as well, easier to clean etc.

[tsbrownie]

@enticed2zeitgeist I admire him for doing the work & not just talking. Other ways to get results are static inverted V's, dynamic V's, more batteries, etc. Trade lower tech for reliability. Uses up front $'s rather than on-going tech/maintenance. I did the battery option almost 20 years ago, want to try the inverted V's one of these days. It's just time & money.

[jhs5150]

@tsbrownie That's actually not true. If you go to redrok.com he explains why.

[tsbrownie]

@jhs5150 Went to look and can't find anything specific in that hodgepodge of stuff. I have a bit of experience designing and building solar stuff (enought that people have paid me to do it) and if you look at the total energy cost to track it's high.  You have to include *everything*: energy to write the programs on the computer, the computer to track, the downtime to maintain, the electricity to build & operate, etc. It's way a lot of new solar farms are "fixed".

[jhs5150]

@tsbrownie I'll find it and post the link here. If you're talking about computer programmed tracking, yes you'd have to factor that in but you know as well as I, once a program is written to do it, you only have to modify it to use on another system. You're not going to write a new program.

[tsbrownie]

@jhs5150 Talking about electricity to run the computer / motors. Maintenance includes bearings, motors, etc.

[jhs5150]

@tsbrownie

Here is the quote from his site.

"Many have said that it makes no sense to use a solar tracker with PV systems as it is cheaper to just add an extra panel for every three. To this I say bunk." Using the NREL data:

I find that in Minnesota a single axis tracking PV panel will have a 40% increase in output in December and a 100% increase in June."

Of course your location will have different results.

[tsbrownie]

@jhs5150 Yes you get more power from the panels, BUT the net increase from the system is small or loss. You have to include energy to run the computer/motors, ... Trackers are also limited to the number of panels they can turn because of wind/weight.

With panels at $0.91 / watt or less a fixed 2KW system with 30% more panels would cost $546 extra. Cheaper than a computer, motors, frame, maintenance, ...  A simple manual adjustment for season would add significantly at very low cost.

[arikz22]

HEY

I AM ARIK FROM ISRAEL

CAN U PLS SHARE WITH ME HOW DO U TRACK THE SUN

I WILL PAY FOR UR ADVICE

ARIKZISK@GMAIL.COM

ISRAEL

[aaqilkhan]

@arikz22 - send me an email with details on what exactly you need help with?

[chiunang]

Hello, It seems that you use a DC linear actuator to pan the panel. By calculation the panel moves very slowly along the day, how do you slow down the actuator? as I read from the spec, speed of those actuators is 5mm/sec the slowest, which still seems too fast for this application....

[aaqilkhan]

@chiunang : the actual speed of the panel rotation will depend on how far is the actuator end connected from the axis of rotation. you can adjust speed at the cost of torque and vice versa. comes from high school physics - simple lever mechanism.

[chiunang]

@aaqilkhan Thank you!

[jhs5150]

@chiunang You can use a 36 or 24 volt actuator and run it at 12 volts. It'll work, but slower. Also some of the trackers, such as the Redrok let you adjust the duty cycle from 0-100%.

[ramya330]

hi...im doing it as my final yr project using embedded code n GPS technology.... can u share ur concept of tracking with me?

[MrBlaze001]

nice, well done

[jpm000001]

nice work!

it looks like you're using a linear actuator for the elevation?

and how are you doing the azimuth tracking, with what kind of motor?

[aaqilkhan]

actually, i am using linear actuators for both azimuth and altitude tracking. The controller uses predictive algorithm and computes the current solar position to point the panels to the sun.

[jpm000001]

very nice.

are you using a custom uC and code?

what do you mean by predictive? do you mean once the controller locks onto the sun, it moves by a set amount in the next minute?

also, did you reference a hardware design for the optical tracking somewhere on the internet? I'd be curious b/c I'm looking into making a 2d tracker myself.

thanks!

[aaqilkhan]

I wrote the code myself. The controller does not use optical sensors (because they fail during brief cloudy conditions and lose the sun if its cloudy for a few hours). Instead, i programmed the controller to compute the solar position using astronomical calculations to point to the sun. This one works very effectively. The entire tracker design: electronics, mechanical, software are my creations, done from scratch - not from any reference designs.

[Lubobuba]

@aaqilkhan Very interesting!

I am working on practically the same project. Which algorithm and which microcontroller did you use for the computation?

I am currently analyzing many algorithms, and it turns out, that Roberto Greena's ENEA algorithm is closest to NREL's SPA, but with just a fraction of the computation.

[aaqilkhan]

@Lubobuba: hi there, thanks for ur interest in my solar tracker. i implemented astronomical calculations in my firmware to compute the actual position of the sun in real-time and reposition the panels after the sun shifts by few degrees. i used a PIC18 uCin closed loop operation using angular position sensors.

i'd be interested in knowing how r u doing it?

[Lubobuba]

@aaqilkhan Hi aaqikhan,

I am currently in the mathematics stage of the project, and I am working on precision optimization and computation reductions in MATLAB. So far, I have analyzed two algorithms very thoroughly for the time period between 2010.01.01 - 2020.01.01. The first and perhaps the best-there-is, is NREL's SPA, as mentioned above, whereas the second algorithm evaluated was Roberto Greena's ENEA.

[Lubobuba]

Greena's code is very computationally efficient, several thousand less operations, however, its max error is around 0.003 degrees, whereas SPA's max error is around 0.0003 degrees.

I will post a video with the explanations of the code and info where to get it, but if someone is interested I can send an email ( for non-commercial use strictly).

aaqilkhan, please let me know which code (the astronomical computations I mean) you used, or if possible, send me the code please.

[Lubobuba]

When I finish the code optimization, I will start with building the system. The main electromechanics will be 7.5 degree unipolar stepper motors, geared down 500:1 trough external gearboxes and then geared another 10-20 times in order to achieve accuracy compatible with the accuracy of the algorithm. It will be a demonstration, table-top system. The purpose of it is to evaluate different solar tracking strategies - PASSIVE as is yours currently, ACTIVE through feedback sensors etc...

[Lubobuba]

...The firmware will be one or more pic's (18f45k20's) and most probably, a rabbit RCM5600W will be the master device, controlling the slave pics, and interactively exchanging data with the net, and providing the web-based user interface. Many other small elements will have to be mentioned, but in general, that is what I am doing.

Regards!